[tor-dev] Creating custom Tor Browser settings profile

Hi I was wondering if Tor Broswer supports environment variables to customize about:config settings. The idea is to ship an explicitly labelled, custom profile one day to allow users seamless access to localhost daemons (like zeronet) by changing network.proxy.no_proxies_on to 0 - so they don't have to jump thru hoops or install foreign code like foxyproxy. At the same time, a separate browser profile affords regular users protection by keeping these fingerprinatble, non default settings contained and only used when the user needs them. Any way to do this?